U.S. patent application number 17/529134 was filed with the patent office on 2022-05-26 for single line drive circuit enabling identical actuator orientation.
The applicant listed for this patent is Magnecomp Corporation. Invention is credited to Kuen Chee Ee, David Glaess, Piyawech Keawlai, Treesoon Kotchaplayuk, Johnathan Hy-tho Phu.
Application Number | 20220165930 17/529134 |
Document ID | / |
Family ID | 1000006025331 |
Filed Date | 2022-05-26 |
United States Patent
Application |
20220165930 |
Kind Code |
A1 |
Kotchaplayuk; Treesoon ; et
al. |
May 26, 2022 |
Single Line Drive Circuit Enabling Identical Actuator
Orientation
Abstract
A driving circuit is described. The driving circuit includes: a
first piezoelectric actuator including at least one piezoelectric
element disposed between a first electrode and a second electrode,
the first electrode configured to connected to a first ground at a
first terminal and the second electrode configured to connected to
an amplifier at a second terminal. The driving circuit includes a
second piezoelectric actuator including at least one piezoelectric
element disposed between a first electrode and a second electrode,
the first electrode configured to connected to a control signal at
a first terminal and the second electrode connected to a second
ground at a second terminal. And, the first terminal of the first
piezoelectric actuator and the first terminal of the second
piezoelectric actuator are configured such that the first
piezoelectric actuator and the second piezoelectric actuator are
symmetrical and have similar polarity.
Inventors: |
Kotchaplayuk; Treesoon;
(Wangnoi, TH) ; Phu; Johnathan Hy-tho; (San
Gabriel, CA) ; Ee; Kuen Chee; (Chino, CA) ;
Glaess; David; (Bangkok, TH) ; Keawlai; Piyawech;
(Wangnoi, TH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Magnecomp Corporation |
Murrieta |
CA |
US |
|
|
Family ID: |
1000006025331 |
Appl. No.: |
17/529134 |
Filed: |
November 17, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63116722 |
Nov 20, 2020 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 41/1876 20130101;
H01L 41/0986 20130101; H01L 41/042 20130101; H01L 41/083 20130101;
G11B 5/483 20150901; H01L 41/0472 20130101 |
International
Class: |
H01L 41/04 20060101
H01L041/04; H01L 41/047 20060101 H01L041/047; H01L 41/083 20060101
H01L041/083; H01L 41/09 20060101 H01L041/09; H01L 41/187 20060101
H01L041/187; G11B 5/48 20060101 G11B005/48 |
Claims
1. A driving circuit comprising: a first piezoelectric actuator
including at least one piezoelectric element disposed between a
first electrode and a second electrode, the first electrode
configured to connected to a first ground at a first terminal and
the second electrode configured to connected to an amplifier at a
second terminal; and a second piezoelectric actuator including at
least one piezoelectric element disposed between a first electrode
and a second electrode, the first electrode configured to connected
to a control signal at a first terminal and the second electrode
connected to a second ground at a second terminal, the first
terminal of the first piezoelectric actuator and the first terminal
of the second piezoelectric actuator are configured such that the
first piezoelectric actuator and the second piezoelectric actuator
are symmetrical and have similar polarity.
2. The driving circuit of claim 1, wherein the first piezoelectric
actuator includes a first piezoelectric element, a second
piezoelectric element, and a third piezoelectric element.
3. The driving circuit of claim 2, wherein the first piezoelectric
element includes a top surface partially covered by a portion of
the first electrode and a portion of the second electrode, the
second electrode covers more of the top surface of the first
piezoelectric element than the first electrode.
4. The driving circuit of claim 2, wherein the first piezoelectric
element and the second piezoelectric element are partially
separated by the first electrode, which is connected to the first
ground.
5. The driving circuit of claim 2, wherein the second piezoelectric
element and the third piezoelectric element are partially separated
by the second electrode.
6. The driving circuit of claim 2, wherein the third piezoelectric
element includes a bottom surface partially covered by a portion of
the first electrode and a portion of the second electrode, the
second electrode covers less of the bottom surface of the third
piezoelectric element than the first electrode.
7. The driving circuit of claim 1, wherein the second piezoelectric
actuator includes a first piezoelectric element, a second
piezoelectric element, and a third piezoelectric element.
8. The driving circuit of claim 7, wherein the first piezoelectric
element includes a top surface partially covered by a portion of
the first electrode and a portion of the second electrode, the
second electrode covers more of the top surface of the first
piezoelectric element than the first electrode.
9. The driving circuit of claim 7, wherein the first piezoelectric
element and the second piezoelectric element are partially
separated by the first electrode.
10. The driving circuit of claim 7, wherein the second
piezoelectric element and the third piezoelectric element are
partially separated by second electrode.
11. The driving circuit of claim 7, wherein the third piezoelectric
element has a bottom surface partially covered by a portion of the
first electrode and a portion of the second electrode, the second
electrode covers less of the bottom surface of the third
piezoelectric element than the first electrode.
12. The driving circuit of claim 1, wherein the first piezoelectric
actuator is configured to be driven in response to the control
signal applied via the second terminal.
13. The driving circuit of claim 1, wherein the second
piezoelectric actuator is configured to be driven in response to
the control signal applied via the first terminal.
14. The driving circuit of claim 1, comprising a head slider,
wherein the first piezoelectric actuator and the second
piezoelectric actuator that are symmetrical and have similar
polarity enable fine radial positioning of the head slider.
15. A suspension device comprising: a driving circuit comprising: a
first piezoelectric actuator including at least one piezoelectric
element disposed between a first electrode and a second electrode,
the first electrode configured to connect to a first ground at a
first terminal and the second electrode configured to connect to a
control signal at a second terminal; and a second piezoelectric
actuator including at least one piezoelectric element disposed
between a first electrode and a second electrode, the first
electrode configured to connect to a control signal at a first
terminal and the second electrode configured to connect to a second
ground at a second terminal, the first terminal of the first
piezoelectric actuator and the first terminal of the second
piezoelectric actuator are configured such that the first
piezoelectric actuator and the second piezoelectric actuator are
symmetrical and have similar polarity.
16. The suspension device of claim 15, wherein the first
piezoelectric actuator includes a first piezoelectric element, a
second piezoelectric element, and a third piezoelectric
element.
17. The suspension device of claim 15, wherein the second
piezoelectric actuator includes a first piezoelectric element, a
second piezoelectric element, and a third piezoelectric
element.
18. The suspension device of claim 15, wherein the first
piezoelectric actuator is configured to be driven in response to
the control signal applied via the second terminal.
19. The suspension device of claim 15, wherein the second
piezoelectric actuator is configured to be driven in response to
the control signal applied via the first terminal.
20. The suspension device of claim 15, comprising a head slider,
wherein the first piezoelectric actuator and the second
piezoelectric actuator that are symmetrical and have similar
polarity enable fine radial positioning of the head slider.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 63/116,722 filed on Nov. 20, 2020, which is hereby
incorporated by reference in its entirety.
FIELD
[0002] This disclosure relates to the field of piezoelectric
actuators. More particularly, this disclosure relates to improving
performance of piezoelectric actuators.
DESCRIPTION OF RELATED ART
[0003] A hard disk drive is known as a type of information storage
device. A hard disk drive typically includes one or more magnetic
disks rotatably mounted in association with a spindle and one or
more actuator assemblies for positioning a magnetic transducer, or
head, relative to concentric circular data tracks on a magnetic
medium-bearing surface of each disk.
[0004] The recording densities of hard disk drives have been
increasing with advances in personal computers, so that data tracks
are becoming increasingly more densely positioned on the disks, and
the tracks themselves are becoming physically narrower. As a
result, maintaining the transducer or head in an accurate
track-following position for purposes of reading and writing, is
becoming more difficult. To accommodate the needed increasingly
finer adjustments in the position of the magnetic head, a precision
positioning actuator has been introduced. For such an actuator, a
single piezoelectric actuator assembly is generally employed. The
piezoelectric actuator forms a part of a head gimbal assembly which
moves the head transverse to a track to provide fine radial
positioning of a head in reference to a track.
SUMMARY
[0005] A driving circuit is described. The driving circuit
includes: a first piezoelectric actuator including at least one
piezoelectric element disposed between a first electrode and a
second electrode, the first electrode configured to connected to a
first ground at a first terminal and the second electrode
configured to connected to an amplifier at a second terminal. The
driving circuit includes a second piezoelectric actuator including
at least one piezoelectric element disposed between a first
electrode and a second electrode, the first electrode configured to
connected to a control signal at a first terminal and the second
electrode connected to a second ground at a second terminal. And,
the first terminal of the first piezoelectric actuator and the
first terminal of the second piezoelectric actuator are configured
such that the first piezoelectric actuator and the second
piezoelectric actuator are symmetrical and have similar
polarity.
[0006] In some examples of the driving circuit, the first
piezoelectric actuator includes a first piezoelectric element, a
second piezoelectric element, and a third piezoelectric element.
The first piezoelectric element may include a top surface partially
covered by a portion of the first electrode and a portion of the
second electrode, where the second electrode covers more of the top
surface of the first piezoelectric element than the first
electrode. The first piezoelectric element and the second
piezoelectric element are partially separated by the first
electrode, which is connected to the first ground. The second
piezoelectric element and the third piezoelectric element may be
partially separated by the second electrode. The third
piezoelectric element may include a bottom surface partially
covered by a portion of the first electrode and a portion of the
second electrode, where the second electrode covers less of the
bottom surface of the third piezoelectric element than the first
electrode.
[0007] In some examples of the driving circuit, the second
piezoelectric actuator includes a first piezoelectric element, a
second piezoelectric element, and a third piezoelectric element.
The first piezoelectric element may include a top surface partially
covered by a portion of the first electrode and a portion of the
second electrode, where the second electrode covers more of the top
surface of the first piezoelectric element than the first
electrode. The first piezoelectric element and the second
piezoelectric element are partially separated by the first
electrode. The second piezoelectric element and the third
piezoelectric element may be partially separated by second
electrode. The third piezoelectric element may have a bottom
surface partially covered by a portion of the first electrode and a
portion of the second electrode, where the second electrode covers
less of the bottom surface of the third piezoelectric element than
the first electrode.
[0008] In some examples of the driving circuit, the first
piezoelectric actuator is configured to be driven in response to a
control signal applied via the second terminal from the amplifier.
In some examples of the driving circuit, the second piezoelectric
actuator is configured to be driven in response to a control signal
applied via the first terminal from the amplifier. In some
examples, the driving circuit also includes a head slider. The
similar polarity and the symmetry of the first piezoelectric
actuator and the second piezoelectric actuator enable fine radial
positioning of the head slider.
[0009] A suspension device is also provided. The suspension device
includes a driving circuit, which includes a first piezoelectric
actuator comprising at least one piezoelectric element disposed
between a first electrode and a second electrode, the first
electrode connected to a first ground at a first terminal and the
second electrode connected to an amplifier at a second terminal.
The driving circuit also includes a second piezoelectric actuator
comprising at least one piezoelectric element disposed between a
first electrode and a second electrode. The first electrode is
connected to the amplifier at a first terminal and the second
electrode connected to a second ground at a second terminal. The
first terminal of the first piezoelectric actuator and the first
terminal of the second piezoelectric actuator are positioned such
that the first piezoelectric actuator and the second piezoelectric
actuator have similar polarity and orientation.
[0010] While multiple examples are disclosed, still other examples
of the present disclosure will become apparent to those skilled in
the art from the following detailed description, which shows and
describes illustrative examples of this disclosure. Accordingly,
the drawings and detailed description are to be regarded as
illustrative in nature and not restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In order to describe the manner in which the above-recited
and other advantages and features of the disclosure can be
obtained, a more particular description of the principles described
above will be rendered by reference to specific examples
illustrated in the appended drawings. These drawings depict only
example aspects of the disclosure and are therefore not to be
considered as limiting of its scope. The principles are described
and explained with additional specificity and detail using the
following drawings.
[0012] FIG. 1 illustrates a side sectional view of a first
piezoelectric actuator for a driving circuit, in accordance with an
example of the disclosure.
[0013] FIG. 2 illustrates a side sectional view of a second
piezoelectric actuator, in accordance with an example of the
disclosure.
[0014] FIG. 3 illustrates a side sectional view of a first
piezoelectric actuator, in accordance with an example of the
disclosure.
[0015] FIG. 4 illustrates a side sectional view of a second
piezoelectric actuator, in accordance with an example of the
disclosure.
[0016] FIG. 5 illustrates a driving circuit architecture, in
accordance with an example of the disclosure.
[0017] FIG. 6 illustrates a side sectional view of a first
piezoelectric actuator of the driving circuit architecture of FIG.
5, in accordance with an example of the disclosure.
[0018] FIG. 7 illustrates a side sectional view of a second
piezoelectric actuator of the driving circuit architecture of FIG.
5, in accordance with an example of the disclosure.
[0019] FIG. 8 is a graph of the PZT frequency response function of
a suspension incorporating the driving circuit architecture, in
accordance with an example of the disclosure.
[0020] FIG. 9 is a graph of the PZT frequency response function of
a suspension incorporating the driving circuit architecture, in
accordance with an example of the disclosure.
[0021] FIG. 10 is a table illustrating a stroke of a suspension
incorporating the driving circuit according to some embodiments
described herein, in accordance with an example of the
disclosure.
[0022] FIG. 11 is a graph comparing the PZT frequency response
function of a suspension incorporating, according to a
simulation.
DETAILED DESCRIPTION
[0023] FIG. 1 illustrate a side sectional view of a first
piezoelectric actuator 120 having a first polarity. The first
piezoelectric actuator 120 has a first electrode 112 that is
configured to connected to a first reference potential, for
example, a zero potential (e.g., a ground). The first piezoelectric
actuator 120 also has a second electrode 114 is configured to
connect to a control signal 130. The first piezoelectric actuator
120 includes a first piezoelectric element 122, a second
piezoelectric element 124, and a third piezoelectric element 126.
The first piezoelectric element 122 has a top surface partially
covered by a portion of the first electrode 112 and a portion of
the second electrode 114. The second electrode 114 covers more of
the top surface of the first piezoelectric element 122 than the
first electrode 112. The first piezoelectric element 122 and the
second piezoelectric element 124 are partially separated by the
first electrode 112. Moreover, the second piezoelectric element 124
and the third piezoelectric element 126 are partially separated by
second electrode 114. The third piezoelectric element 126 has a
bottom surface partially covered by a portion of the first
electrode 112 and a portion of the second electrode 114. The second
electrode 114 covers less of the bottom surface of the third
piezoelectric element 126 than the first electrode 112.
[0024] Under the illustrated poling directions in FIG. 1, when a
positive voltage is applied and the electric field is in the same
direction as the poling direction across the first electrode 112
and the second electrode 114, all three piezoelectric elements 122,
124, and 126 expand in the longitudinal direction.
[0025] FIG. 2 illustrates a side sectional view of a second
piezoelectric actuator 125 having a second polarity opposite the
first polarity. The second piezoelectric actuator 125 has a first
electrode 116 that is configured to connect to a first reference
potential, for example, a zero potential (e.g., the second ground
180). The second piezoelectric actuator 125 also has a second
electrode 118 is connected to a control signal 130. The second
piezoelectric actuator 125 includes a first piezoelectric element
132, a second piezoelectric element 134, and a third piezoelectric
element 136. The first piezoelectric element 132 has a top surface
partially covered by a portion of the first electrode 116 and a
portion of the second electrode 118.
[0026] The second electrode 118 covers more of the top surface of
the first piezoelectric element 132 than the first electrode 116.
The first piezoelectric element 132 and the second piezoelectric
element 134 are partially separated by the first electrode 116.
Moreover, the second piezoelectric element 134 and the third
piezoelectric element 136 are partially separated by second
electrode 118. The third piezoelectric element 136 has a bottom
surface partially covered by a portion of the first electrode 116
and a portion of the second electrode 118. The second electrode 118
covers less of the bottom surface of the third piezoelectric
element 136 than the first electrode 116.
[0027] Under the illustrated poling directions as illustrated in
FIG. 2, when a positive voltage is applied and the electric field
is in the opposite direction of the poling direction across the
first electrode 116 and the second electrode 118, all three
piezoelectric elements 132, 134, and 136 contract in the
longitudinal direction.
[0028] FIG. 3 illustrates a side sectional view of the first
piezoelectric actuator 220 for a driving circuit. The first
piezoelectric actuator 220 has a first electrode 212 that is
configured to connect to a first reference potential, for example,
a zero potential (e.g., a ground). The first piezoelectric actuator
220 also has a second electrode 214 connected to a control signal
230. The first piezoelectric actuator 220 includes a first
piezoelectric element 222, a second piezoelectric element 224, and
a third piezoelectric element 226. The first piezoelectric element
222 has a top surface partially covered by a portion of the first
electrode 212 and a portion of the second electrode 214.
[0029] The second electrode 214 covers more of the top surface of
the first piezoelectric element 222 than the first electrode 212.
The first piezoelectric element 222 and the second piezoelectric
element 224 are partially separated by the first electrode 212.
Moreover, the second piezoelectric element 224 and the third
piezoelectric element 226 are partially separated by second
electrode 214. The third piezoelectric element 226 has a bottom
surface partially covered by a portion of the first electrode 212
and a portion of the second electrode 214. The second electrode 214
covers less of the bottom surface of the third piezoelectric
element 226 than the first electrode 212.
[0030] Under the illustrated poling directions in FIG. 3, when a
positive voltage is applied and the electric field is in the same
direction as the poling direction across the first electrode 212
and the second electrode 214, all three piezoelectric elements 222,
224, and 226 expand in the longitudinal direction.
[0031] FIG. 4 illustrates a side sectional view of the second
piezoelectric actuator 225 of the driving circuit, in accordance
with an example of the disclosure. The second piezoelectric
actuator 225 has a first electrode 216 that is connected to a first
reference potential, for example, a zero potential (e.g., a
ground). The second piezoelectric actuator 225 also has a second
electrode 218 connected to the control signal 230. The second
piezoelectric actuator 225 includes a first piezoelectric element
322, a second piezoelectric element 324, and a third piezoelectric
element 326. The first piezoelectric element 322 has a top surface
partially covered by a portion of the first electrode 216 and a
portion of the second electrode 218.
[0032] In contrast to the first piezoelectric actuator 220 of FIG.
3, the second electrode 218 covers less of the top surface of the
first piezoelectric element 322 than the first electrode 216. This
is because the second piezoelectric actuator 225 is rotated 180
degrees from the orientation of the second piezoelectric actuator
125 of FIG. 2. The first piezoelectric element 322 and the second
piezoelectric element 324 are partially separated by the second
electrode 218. Moreover, the second piezoelectric element 324 and
the third piezoelectric element 326 are partially separated by
first electrode 216. The third piezoelectric element 326 has a
bottom surface partially covered by a portion of the first
electrode 216 and a portion of the second electrode 218. The second
electrode 218 covers more of the bottom surface of the third
piezoelectric element 326 than the first electrode 216.
[0033] Under the illustrated poling directions in FIG. 4, when a
positive voltage is applied such that the electric field is in an
opposite direction of the poling direction across the first
electrode 216 and the second electrode 218, all three piezoelectric
elements 322, 324, and 326 contract in the longitudinal
direction.
[0034] FIG. 5 is a driving circuit 500, in accordance with an
example of the disclosure. The driving circuit 500 includes a first
piezoelectric actuator 520 and a second piezoelectric actuator 525
configured to move a head slider 540 of a suspension for a hard
disk drive. The first piezoelectric actuator 520 and the second
piezoelectric actuator 525 are each electrically coupled with the
driving circuit 500. As a result, the first piezoelectric actuator
520 and the second piezoelectric actuator 525 are responsive to an
applied voltage control signal applied to affect a desired physical
displacement of a head slider using techniques including those know
in the prior art. This is discussed in greater detail below with
respect to FIGS. 6-7.
[0035] The driving circuit 500 is configured to be incorporated in
a suspension device of a hard disk drive, such as a head gimbal
assembly. The first piezoelectric actuator 520 includes a first
terminal 521 (or reference terminal), and a second terminal 523.
The first piezoelectric actuator 520 is connected to a first ground
contact 570 at the first terminal 521. The first piezoelectric
actuator 520 is also connected to a control signal 530 at the
second terminal 523. The second piezoelectric actuator 525 includes
a first terminal 527 (e.g., a reference terminal), and a second
terminal 529. The second piezoelectric actuator 525 is connected to
a second ground contact 580 at the second terminal 529. The second
piezoelectric actuator 525 is also connected to the control signal
530 at the first terminal 527. In other words, the first and second
terminals 527, 529 of the second piezoelectric actuator 525 are
switched and the first and second piezoelectric actuators 520, 525
have the same polarity and orientation. And, the active portions
528, 538 are arranged such that they are symmetrical. This is
further illustrated in FIGS. 6-7.
[0036] FIG. 6 illustrates a side sectional view of the first
piezoelectric actuator 520 of the driving circuit architecture 500,
in accordance with an example of the disclosure. The first
piezoelectric actuator 520 has a first electrode 512 that is
connected to a first reference potential, for example, zero
potential (e.g., through the first ground contact 570). The first
piezoelectric actuator 520 also has a second electrode 514
connected to the control signal 530. The first piezoelectric
actuator 520 includes a first piezoelectric element 522, a second
piezoelectric element 524, and a third piezoelectric element 526.
The first piezoelectric element 522 has a top surface partially
covered by a portion of the first electrode 512 and a portion of
the second electrode 514.
[0037] The second electrode 514 covers more of the top surface of
the first piezoelectric element 522 than the first electrode 512.
The first piezoelectric element 522 and the second piezoelectric
element 524 are partially separated by the first electrode 512,
which is grounded. Moreover, the second piezoelectric element 524
and the third piezoelectric element 526 are partially separated by
second electrode 514. The third piezoelectric element 526 has a
bottom surface partially covered by a portion of the first
electrode 512 and a portion of the second electrode 514. The second
electrode 514 covers less of the bottom surface of the third
piezoelectric element 526 than the first electrode 512, which is
grounded. The first piezoelectric actuator 520 includes an active
portion 528 that includes a portion of the first piezoelectric
element 522 between the second electrode 514 and the first
electrode 512; a portion of the second piezoelectric element 524
between the first electrode 512 and the second electrode 514; and a
portion of the third piezoelectric element 526 between the second
element 514 and the first element 512.
[0038] Under the illustrated poling directions in FIG. 6, when a
positive voltage is applied such that the electric field is in the
same direction as the poling direction across the first electrode
512 and the second electrode 514, all three piezoelectric elements
522, 524, and 526 expand in the longitudinal direction.
[0039] FIG. 7 illustrates a side sectional view of the second
piezoelectric actuator 525 of the driving circuit 500, in
accordance with an example of the disclosure. The second
piezoelectric actuator 525 has a first electrode 516 that is
connected to the control signal 530. The second piezoelectric
actuator 525 also has a second electrode 518 connected to a first
reference potential, for example, zero potential (e.g., through the
second ground contact 580). The second piezoelectric actuator 525
includes a first piezoelectric element 532, a second piezoelectric
element 534, and a third piezoelectric element 536. The first
piezoelectric element 532 has a top surface partially covered by a
portion of the first electrode 516 and a portion of the second
electrode 518.
[0040] The second (grounded) electrode 518 covers more of the top
surface of the first piezoelectric element 532 than the first
electrode 516. The first piezoelectric element 532 and the second
piezoelectric element 534 are partially separated by the first
electrode 516. Moreover, the second piezoelectric element 534 and
the third piezoelectric element 536 are partially separated by
second electrode 518. The third piezoelectric element 536 has a
bottom surface partially covered by a portion of the first
electrode 516 and a portion of the second electrode 518. The second
electrode 518 covers less of the bottom surface of the third
piezoelectric element 536 than the first electrode 516. The second
piezoelectric actuator 525 includes an active portion 538 that
includes a portion of the piezoelectric element 532 between the
second electrode 518 and the first electrode 516; a portion of the
second piezoelectric element 534 between the first electrode 516
and the second electrode 518; and a portion of the third
piezoelectric element 536 between the second element 518 and the
first element 516.
[0041] Under the illustrated poling directions in FIG. 7, when a
positive voltage is applied such that the electric field is in
opposite direction of poling direction across the first electrode
516 and the second electrode 518, all three piezoelectric elements
532, 534, and 536 contract in the longitudinal direction.
[0042] Referring back to FIG. 5, the first piezoelectric actuator
520 and the second piezoelectric actuator 525 are similarly poled.
Moreover, the structures of the first piezoelectric actuator 520
and the second piezoelectric actuator 525 are arranged in a
symmetrical orientation and each having the same polarity. The
first piezoelectric actuator 520 is configured to be driven in
response to a control signal 530 applied via the second (input)
terminal 523. Similarly, the second piezoelectric actuator 525 is
configured to be driven in response to a control signal 530 applied
via the first (input) terminal 527. The control signals affect
mechanical deformation of the piezoelectric elements, as discussed
above, of the first and second piezoelectric actuators 520, 525.
The similar polarity and the symmetry of the first piezoelectric
actuator 520 and the second piezoelectric actuator 525 enable fine
radial positioning of the head slider 540 in direction 510. The
similar polarity and the symmetry of the first piezoelectric
actuator 520 and the second piezoelectric actuator 525 also improve
sway mode gain and torsion mode gain sensitivity, as compared to
current systems that rely on actuators having an opposite
orientation and asymmetric active portions.
[0043] FIG. 8 is a graph 600 of the PZT frequency response function
(0-80 kHz) of a suspension incorporating driving circuit according
to some embodiments described herein, according to a simulation.
FIG. 9 is a graph 700 of the PZT frequency response function (0-30
kHz) of a suspension incorporating driving circuit according to
some embodiments described herein, according to a simulation. As
indicated in FIG. 9, the suspension exhibited torsion mode gain
sensitivity of 1 dB and sway mode gain sensitivity of 3 dB. The
lower sway mode gain and torsion mode gain sensitivity increase
head positioning control loop bandwidth, which translates to both
lower data seek times and lower susceptibility to vibrations.
[0044] FIG. 10 is a table 800 illustrating the stroke of a
suspension incorporating the driving circuit according to some
embodiments described herein compared to a suspension incorporating
current techniques including asymmetric arrangement of the active
portions and opposite actuator orientation, according to a
simulation. As illustrated herein, the suspension incorporating the
driving circuit according to some embodiments described herein with
actuators with the same orientation and symmetric active portions
exhibited a stroke of 10.05 nm/V. In comparison, the suspension
incorporating the asymmetric arrangement of the active portions of
the actuators exhibited a stroke of 8.99 nm/V. Therefore, the
suspension incorporating the driving circuit according to some
embodiments described herein exhibited a stroke increase. For the
example illustrated in FIG. 10, the driving circuit according to
embodiments described herein exhibited stroke increase of 11%
compared to the suspension incorporating the asymmetric arrangement
and opposite actuator orientation.
[0045] FIG. 11 is a graph 900 comparing the PZT frequency response
function of a suspension incorporating driving circuit 500 to the
PZT frequency response function of a suspension incorporating
current techniques including asymmetric arrangement of the active
portions and opposite actuator orientation, according to a
simulation. As illustrated in FIG. 11, the suspension incorporating
driving circuit according to some embodiments described herein
exhibited lower sway mode gain and torsion mode gain
sensitivity.
[0046] It will be understood that the terms "generally,"
"approximately," "about," "substantially," and "coplanar" as used
within the specification and the claims herein allow for a certain
amount of variation from any exact dimensions, measurements, and
arrangements, and that those terms should be understood within the
context of the description and operation of the present
disclosure.
[0047] It will further be understood that terms such as "top,"
"bottom," "above," and "below" as used within the specification and
the claims herein are terms of convenience that denote the spatial
relationships of parts relative to each other rather than to any
specific spatial or gravitational orientation. Thus, the terms are
intended to encompass an assembly of component parts regardless of
whether the assembly is oriented in the particular orientation
shown in the drawings and described in the specification, upside
down from that orientation, or any other rotational variation.
[0048] All features disclosed in the specification, including the
claims, abstract, and drawings, and all the steps in any method or
process disclosed, may be combined in any combination, except
combinations where at least some of such features and/or steps are
mutually exclusive. Each feature disclosed in the specification,
including the claims, abstract, and drawings, can be replaced by
alternative features serving the same, equivalent, or similar
purpose, unless expressly stated otherwise. Thus, unless expressly
stated otherwise, each feature disclosed is one example only of a
generic series of equivalent or similar features.
[0049] It will be appreciated that the term "example" as used
herein should not be construed to mean that only a single example
having a single essential element or group of elements is
presented. Similarly, it will also be appreciated that the term
"present disclosure" encompasses a number of separate innovations
which can each be considered separate examples. Although the
present disclosure has thus been described in detail with regard to
the preferred examples and drawings thereof, it should be apparent
to those skilled in the art that various adaptations and
modifications of the present disclosure may be accomplished without
departing from the spirit and the scope of the present disclosure.
Accordingly, it is to be understood that the detailed description
and the accompanying drawings as set forth hereinabove are not
intended to limit the breadth of the present disclosure, which
should be inferred only from the following claims and their
appropriately construed legal equivalents.
* * * * *